That put him at odds with Trump, who had told Flynn's deputy, K.T. McFarland, that she could stay.

Trump appeared to refer to Harward earlier in the day at a presidential news conference, saying: "I have somebody that I think will be outstanding for the position."

The president also made clear why he asked Flynn to resign, saying it was because the retired lieutenant general had not been completely truthful with Pence about his conversations with the Russian ambassador to the United States, Sergei Kislyak.

"The thing is, he didn't tell our vice president properly, and then he said he didn't remember. So either way, it wasn't very satisfactory to me," Trump said.

(Reporting by John Walcott and Steve Holland; Editing by Eric Walsh and Peter Cooney)